This invention relates to the cryogenic comminution of rubber and more particularly to a process by which scrap rubber can by cryogenically comminuted into a powder suitable for use in a variety of applications.
At the present time, very little scrap rubber is recycled because of the difficulty of pulverizing or comminuting it to particles of a size that are suitable for reuse. Scrap rubber can be cut or shredded into chips of about 2xe2x80x3 to 3xe2x80x3 in size but, in general, such chips are not fine enough for reuse. In most instances, the particles must be in the range of about 10 to about 100 mesh ASTM in size to be suitable for reuse.
Because of the difficulty of comminuting scrap rubber, most of it is disposed of in land-fill sites. The material is not suited to such disposal because it does not decompose or change in composition over time even when mixed with soil or other forms of manufactured waste. Furthermore, any buried rubber tends to rise to the surface over time due to its inherent dynamic buoyancy.
We have invented a process for the cryogenic comminution of scrap rubber into a powder suitable for use in a variety of applications. Briefly our process involves the steps of cooling chips of scrap rubber to a temperature in the range of about minus 90 to about minus 110 degrees Celsius; and comminuting the cooled rubber chips to powder substantially of a size of less than about 10 mesh ASTM.
The apparatus used to carry out the processes of my invention is described with reference to the accompanying drawings in which FIGS. 1, 2 and 3 are schematic elevations of the apparatus used to carry out three variations of the process.